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Sheet-2
LIGHT
CONCAVE & CONVEX MIRROR
CONCAVE & CONVEX LENS
Mixed Questions
1. A ray of light incident normally on a mirror retraces its path .
Why?
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2. What is the focal length of a convex mirror of radius of curvature
30 cm.
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3. A concave mirror produces 50 cm tall image of an object 20 cm
in height. Find magnification .
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4. What is the focal length of a lens of number +2 .
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5. Image formed by a convex lens is always real . Is it true?
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6. You are given a concave mirror of focal length 10 cm. What
should be the range of distance of the object if the mirror is to obtain
an image of the object?
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7. Which lens can be used as the magnifying glass ?
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8. No matter how far you stand from a lens, your image appears
erect. What type of lens is this?
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9. A ray of light suffer no net deviation on passing through a
rectangular glass slab. Why?
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10. State mirror formula. Will focal length if mirror change on
changing the object distance? If not then why ? What determines the
focal length of the mirror?
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11. Give any two rules for tracing images formed by concave mirror
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12. Why is convex mirror used as a rear-view mirror in vehicles
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13. What is optically denser medium? Does it possess greater mass
density too ?
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14. The RI of glass is 3/2 and the RI of water is 4/3. How much
faster does the light travel in water than in glass.
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15. Calculate the focal length of a lens which when placed in
contact with a lens of focal length 20 cm would form a combination
of power -4 D. Will the lens be convex or concave .
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16. Calculate the distance at which the object should be placed in
front of a concave lens of focal length 30 cm .
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17. State the condition for no refraction
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18. What is linear magnification of a spherical mirror. Explain why
is magnification always positive in case of convex mirror. Why it can
be positive or negative in case of a concave mirror
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19. Draw appropriate figures to illustrate three rules for the
formation of images by a concave lens.
20. An erect image three tines the size of the object is obtained with
a concave mirror of radius of curvature 36 cm. What is the position of the image?
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21. The image of a needle placed 10 cm form a lens is formed on a
wall 20 cm on the other side of the lens. Find focal length of the lens
and size of the image formed if the size of the needle is 2.5 cm.
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22. An object of size 2 cm is placed in front of a convex mirror of
R=20 cm. Its image is formed 8 cm behind the mirror. Find the
distance of the object from the mirror and the size of the image .
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23. Draw course of rays to illustrate the changes in position , size
and nature of the image formed by convex mirror when (i) the object
is at infinity and (ii) the object is at finite distance from the mirror
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24. State the laws of refraction . Define Refractive Index of a medium
Show that 2n is reciprocal of 1n2 .
1
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25. A concave mirror is used as a head mirror by ENT specialists.
The same mirror can also be used as a shaving mirror. Why ?
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26. Which factors determine the focal length of a lens ?
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27. How much time will light take to cross 2 mm thick glass pane
if refractive index of glass is 3/2 ?
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28. How is refractive index of a medium related to velocity of the
light in the medium
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29. With respect to air the RI of ice is 1.31 and that of rock salt is
1.54.Calculate the RI of rock salt w.r.t. ice .
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30. Why does a ray of light bend when it travels from one medium
to another?
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